Thanks pfaffmann!!
Fortunately, I’m not one of those people who gives up easily, although these subsequent problems worry me, especially since I’m not 100% familiar with this platform.
By default, my CloudServer has Apache installed, and if I remove it, it causes problems with CPanel and other features. I tried it during the first installation because I read that nginx was much better and faster, but I had the issues I mentioned. Therefore, I reinstalled the OS on the server and started over, following this recommendation:
It’s not like I have multiple sites, at least not yet, because my CloudServer allows up to 5 accounts.
As for the standard installation, I followed all the steps to install Docker, Discourse, Certbot, and download the Let’s Encrypt certificates, but when I ran discourse-setup, I had to perform the manual configuration following the link above and configuring manually app.yml file to perform the rebuild.